With the growth of demand for network services, services such as IPTV (IP Television) and VoD (Video on Demand) are becoming more and more important. In order to avoid that video quality is deteriorated since too many network services are on line simultaneously and improve subscriber experience, control measures called “admission control” need to be applied at the time of admitting network services of subscribers.
A method for admission control in the prior art is as follows: In an xDSL (generic Digital Subscriber Line, many flavors of Digital Subscriber Line) scenario, video bandwidth is statically divided into unicast bandwidth and multicast bandwidth. A DSLAM (Digital Subscriber Line Access Multiplexer) manages the multicast bandwidth, and a RACS (Resource and Admission Control Sub-System) manages the unicast bandwidth. When a subscriber requests a multicast video, if the traffic of the multicast video already exists on the network, the DSLAM adds the subscriber to a multicast video group. If the subscriber is the first requester of the multicast video, the DSLAM decides whether to admit or refuse the subscriber's request depending on whether remaining multicast bandwidth managed by the DSLAM is sufficient for admitting the subscriber's request. When the subscriber requests a unicast video, whether the unicast bandwidth is currently sufficient for admitting the subscriber's request needs to be queried, and the subscriber's request is refused if the unicast bandwidth is insufficient.
Another method for admission control in the prior art is as follows: In an xDSL scenario, on the basis of statically dividing video bandwidth into unicast bandwidth and multicast bandwidth, dynamic negotiation is allowed between the unicast bandwidth and the multicast bandwidth. A DSLAM manages the multicast bandwidth, and a RACS manages the unicast bandwidth. When a subscriber requests a multicast video, the DSLAM calculates remaining multicast bandwidth, admits the multicast video request if the remaining multicast bandwidth is sufficient, or, attempts to borrow a part of the unicast bandwidth from the RACS for the multicast video if the remaining multicast bandwidth is insufficient, and admits the subscriber's multicast video request if the borrowing succeeds, or refuses the subscriber's request if the negotiation fails.
In the process of implementing the present invention, the inventor finds at least the following problems in the prior art:
In the first method for admission control, if many subscribers would like to watch the unicast video, the unicast bandwidth is insufficient but the multicast bandwidth is surplus; and vice versa, which leads to low utilization of bandwidth. In the second method for admission control, the bandwidth is negotiated between the DSLAM and the RACS only in the xDSL scenario, but not in an FTTx (Fiber To The x, a general name of many flavors of fiber application, such as Fiber to The Building and Fiber to The Home) scenario, which does not fully satisfy operators' requirements for negotiating bandwidth.